In recent years, much attention has been paid to cyclone vacuum cleaners, that is, vacuum cleaners allowing airflow of sucked air to have a whirling component and separating and removing dust from the airflow with a centrifugal force. Vacuum cleaners of this type employ a configuration for generating a whirling air current in a dust collecting case, separating dust from the sucked airflow with a centrifugal force of the whirling air current, and accumulating the separated dust in the dust collecting case.
Recently, a filtration filter formed of a metal plate having small through-holes has been proposed in which the removal of dust attached to the filtration filter is simplified (see, for example, Patent Document 1).
As described in Patent Document 1, when a filtration filter is made of a metal plate having small through-holes, dust attached to the filtration filter can be removed in more simple and easy manner as compared with a filtration filter made of a non-woven fabric.
However, thread-like dust (hair, pet hair, and long thin fiber lint, and the like) sucked during cleaning is guided to through-holes of filtration filter together with sucked airflow and stuck in the through-holes. Then, other dust is attached to the thread-like dust stuck in the through-holes and cotton lint grows large around the stuck thread-like dust as a core. Consequently, when collected dust is discharged, cotton lint, hair and the like hung from the through-holes of the filtration filter, thus making it difficult to discharge the collected dust.
Note here that the thread-like dust used in this description is intended to mean dust having a thin long shape. An example of the thread-like dust includes hair, pet hair, and furthermore thin fiber lint.    Patent document 1; Japanese Patent Unexamined Publication No. 2005-52394